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    <title>Document</title>
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    <script>
        //变量的预解析
        // console.log(a); // undefined    => 没有被定义
        // var a = 10;
        // console.log(a); // 10           => 已经赋值

        /* 赋值式的预解析 */
        // fn();   //fn is not a funtion
        // var fn = function () { console.log("赋值式函数fn"); }
        // fn();

        //在我们的JS当中,代码一旦出错了之后,代码就不会往后面执行了
        // var a = null;
        // console.log(a.length);
        // console.log(111111111111111);
    </script>
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